JP6986011B2 - Speaker diaphragm - Google Patents

Description

The present invention relates to a speaker diaphragm and a method of manufacturing such a diaphragm. More specifically, the present invention relates to a speaker diaphragm provided with a woven fiber body that supports a damping material, but is not limited thereto. The present invention also relates to a speaker drive unit and a speaker housing.

GB1491080 (according to B & W Loudspeakers Limited-or "B & W"-) is from an open mesh woven fiber material reinforced with thermosetting resin so that space is left between adjacent fibers, such as Kevlar®. The made speaker diaphragm is disclosed. The space is partially filled with damping material such as PVA (polyvinyl acetate) emulsion. The space between the threads of the fabric allows for a good bond between the PVA emulsion and the woven fiber material. The British company Bowers & Wilkins (see "B & W] -www.bowers-wilkins.co.uk) incorporates speaker diaphragms made from woven Kevlar® fabric reinforced with resin and covered with PVA. The midrange drive unit is commercialized. The PVA material is smeared over the woven fiber material in one or more layers, typically the PVA material is about 10% of the total mass of the speaker diaphragm. It will form ~ 15%. The result is useful break-up behavior (break-up behaviour), more subdued coloration, and emitted sound, as described in more detail below. A slightly flexible cone (“B & W Kevlar cone”) that exhibits a more uniform dispersion of Available in .html).

The continuous vibration of the speaker diaphragm, independent of the input signal applied, responds to the "time-sounding" -a form of coloration-and the resulting given input signal. This can lead to a decrease in the clarity of the sound produced and the exact reproducibility of the sound from the input signal. The PVA material provides damping, but the anisotropic properties of the B & W Kevlar cones are cited as important: because they are woven, the mechanical properties of the B & W Kevlar cones are the orientation of the fibers. Depends on the angle to. The sound wave travels through the material of the cone at different speeds depending on the direction of travel. Therefore, the reflection of sound waves traveling over the body of the B & W Kevlar cone occurs at different points around the edge of the cone, reducing the less symmetric pattern of sound waves and the effect of the formation of standing waves on sound. Bring. Otherwise, the listener receives less sound than would otherwise be produced by the delayed energy radiated by the cone. As a result, there is less unwanted "time obscure" noise. The cone therefore produces a radiating sound that can deliver significantly clearer and finer details. Design details stated to provide quality control of acoustic reproduction include the type of weave, the geometry of the cone, and the choice of reinforcing resin and damping material type.

B & W Kevlar cones are used in many of B & W's products and are widely used in midrange drive units supplied to B & W speakers (www.bowers-wilkins.eu/Speakers/Thetre_Solutions/FPM_VM_Series/Technol). reference). Kevlar not only has the above-mentioned advantageous properties, but also has an attractive and unique appearance, which makes Kevlar suitable for use on the forward sound emitting surface of the diaphragm of the speaker drive unit. To. However, Kevlar is an expensive material and it would be beneficial to have an alternative material for this application that could be used in embodiments that provide similar or better acoustic performance. It should also be beneficial for such materials to have an appearance suitable for use in high fidelity environments, as well as to achieve technical performance and meet the technical features required for it.

The present invention is intended to alleviate one or more of the above problems. Alternatively, or further, the present invention is intended to provide an improved speaker diaphragm. Alternatively, or in addition, the invention is intended to provide an alternative to the B & W Kevlar cone described above, which is substantially identical or has better acoustic performance.

The present invention provides a speaker diaphragm comprising a woven fiber body having a forward sound emitting surface and a backward surface supporting the damping material, the damping material preferably forming the shape of the diaphragm. According to one aspect of the invention that is important but not always essential, the woven fiber is made of a metal-coated non-metal fiber material, which metal-coated non-metal fiber material is exposed to natural light. Light from different light sources is preferably one in which the vibrating plate appears to have a shimmering appearance, for example, as perceived by the naked eye when illuminated by light.

Potential that you do not need to use Kevlar, which is expensive and has limitations on how it can be presented (especially keeping in mind that Kevlar's natural color is cream yellow). It is possible to make speaker diaphragms using such metal-coated non-metal fiber materials that perform well, if not better, than B & W's Kevlar cones, which have the advantages of. The present invention not only has the benefit of providing an alternative to the prior art Kevlar fiber cones, but also proposes a speaker diaphragm with a particularly unique and attractive appearance. Elongates of fibers woven to form woven fibers are woven in and out of each other so that the surface of the diaphragm has a non-smooth geometry at the local level (eg, on a micrometer or millimeter scale). Be done. Non-smooth geometry means that the incident light received at a given angle of incidence (relative to the axis or forward of the diaphragm) is reflected by the metal coating in significantly different directions between relatively close locations on the diaphragm. Means. The outer metal surface is preferably a specularly reflective surface, eg, such that the surface has a mirror-like appearance as opposed to a less glossy appearance. Thus, a diaphragm, whether natural light or light from a different light source, can have an attractive shimmering appearance or an unusually noticeable appearance when illuminated by light. In addition, the damping material may have an unattractive appearance and / or the potential for discoloration over time. The use of speaker diaphragms with a glittering, visually noticeable, forward-facing surface masks or at least from there the perhaps unattractive appearance of the rear damping material, which would otherwise be more eye-catching. It may have the additional advantage of providing something that distracts. In another aspect of the invention, the woven fiber may be formed of a material that is not in the form of a metal-coated non-metal fiber material but still provides benefits.

According to another aspect of the invention, which is important but not always essential, the mass of the layer of damping material exceeds the mass of the woven fiber by more than 25%. Surprisingly, it has been found that having a relatively high ratio of the mass of the damping material layer to the mass of the woven fiber can provide improved acoustic performance in the embodiments of the present invention. In one embodiment of the invention for a 6 inch drive unit, the mass of the woven fiber and the mass of the vibration damping material can be 3 grams and 5 grams, respectively. By comparison, the mass of the woven fiber of a 6-inch B & W Kevlar cone (in the prior art) and the mass of the anti-vibration material are 6 grams and 1 gram, respectively. Thus, B & W Kevlar cones have damping material added to provide damping rather than structure and have some of the lowest levels of stiffness and structural support provided by the woven fiber. In embodiments of this aspect of the invention, the properties of the damping material play a much greater role in the physical structure and acoustic performance of the diaphragm, with the woven fiber playing a smaller role. One role that may be the main role of the woven fiber of the present invention may be that the woven fiber acts as a substrate or skeleton structure to support the damping material that forms most of the diaphragm. .. One role that may be the second role of the woven fiber is that the woven fiber provides a aesthetically pleasing positive surface.

As mentioned above, much more than previously recommended in the context of B &W's Kevlar cone design, which includes a woven fiber with a backward facing surface that supports only a layer of relatively thin damping material. It has been found that having a relatively large amount of damping material can be surprisingly beneficial. The mass of the layer of damping material may exceed the mass of the woven fiber by more than 50%. The layer of damping material may have at least twice the mass of the woven fiber. The mass of the layer of damping material may be, for example, in the range of ^{100 to 500 g / m 2.} The mass of the woven fiber may be between 25% and 80% of the mass of the layer of damping material.

The thickness of the layer of the damping material may exceed the thickness of the woven fiber body. The thickness of the layer of the damping material may exceed, for example, 0.2 mm. The thickness of the layer of damping material may be less than 0.5 mm.
The woven fiber body may form a forward sound emitting surface of the diaphragm. The layer of damping material may form a rearward surface of the diaphragm. Therefore, the woven fiber body may not be present on the rearward surface of the diaphragm, as may be the case when the diaphragm is in the form of a sandwich structure.
The damping layer may have a single structure. The damping layer may have a monolithic structure having a uniform composition. Therefore, the damping layer may be such that it has little or preferably no fibrous material in its structure.
As mentioned above, in some embodiments, the woven fiber may be made from a non-metal fiber material. The fiber body may be made of metal-coated fibers. When the woven fiber body is formed of the metal-coated fibers, the thickness of the metal coating may be less than 10 μm. The metal coating may have a thickness of less than 1 μm.

Woven fibers can include fibers and resins, for example fibers that are (at least partially) incorporated into a cured resin substrate. The resin may be a phenol resin. The resin can contribute to the rigidity of the woven fiber body. Therefore, the resin can be in the form of a reinforcing resin. The fibrous body and resin can be in the form of a composite structure.
The metal part may be protected by a layer of lacquer if the woven fiber body is formed of fibers that are at least partially made of metal. The layer of lacquer can contribute to the rigidity of the woven fiber material. If the fibrous material is further reinforced by using a reinforcing resin in addition to the lacquer, it may be possible to use less reinforcing resin per unit area of the woven fiber material. The lacquer is preferably translucent and may have a clear color, eg, substantially transparent. The mass per unit area of the resin may exceed the mass per unit area of the lacquer by 5 times or less. The total mass of the resin and the lacquer per unit area may be in the range of ^{20 to 60 g / m 2.}

The diaphragm may have a flat shape. The diaphragm may have an overall conical shape. The diaphragm may have a diameter of at least about 50 mm. The diaphragm may have a diameter of about 200 mm or less.
The woven fiber body may be formed of a glass fiber material. Glass fibers are readily available and relatively inexpensive, but are typically transparent, thus allowing light to be transmitted from one side of the woven fiber material to the other side through the glass. enable. In some cases it may be inconvenient to allow light to pass through and / or from the damping material on the backward surface of the woven fiber, in which case the fiberglass indicates the best material choice. Can be perceived as not. However, if the fiberglass material is covered with an opaque coating as provided by the metal coating proposed above, such potential drawbacks can be mitigated or overcome.

The woven fiber body may have a relatively regular weave. For example, the density of thread lengths per unit area may be substantially constant across the surface of the diaphragm. A collection of fibers that together form an elongate of a single material that is interwoven in and out of an elongate of another material can itself be considered a single thread in this context.
The weaving nature of the fibrous body of the diaphragm can be such that long objects of material weave into and out of each other to form the body. There may be gaps between adjacent long objects of material. The woven fiber body can define an array of such gaps. It will be appreciated that the gap array typically has a relatively complex three-dimensional geometry and is typically not a regular array. Each gap is typically formed by a pair of adjacent fibers that intersect with another pair of adjacent fibers, but can have a maximum dimension of at least 50 μm, preferably at least 100 μm. The damping material may fill substantially all of the gaps so defined.

The damping material can have a dynamic loss rate of at least 0.25 at frequencies between 1 kHz and 8 kHz. For example, damping material can have a dynamic loss rate of at least 0.5 at frequencies between 3 kHz and 6 kHz. The loss rate may be greater than 0.75 at frequencies within the operating frequency range of the diaphragm. Such damping materials can provide particularly strong damping at frequencies where the vibration of the diaphragm can otherwise begin to break up (ie, deviate from simple piston-like behavior). The damping material may be an elastomer material. The damping material may be in the form of a synthetic resin. The damping material may be in the form of a suitable polymer. Vinyl polymers may be appropriate. The damping material may be a high damping polymer material such as a PVA (polyvinyl acetate) material. The discoloration of such materials over time means that their use in hi-fi speaker diaphragms is usually limited to areas that are not visible in normal use. Accordingly, there may be embodiments of the invention in which the damping material is beneficially masked or concealed or otherwise disguised by a metal-coated fibrous body.

The thickness of the damping material may be substantially constant, if not substantially, over most, if not all, of the backward surface on which the damping material is supported. It will be appreciated that slight changes in thickness resulting from the weaving properties of the fibers and any gaps in the weave should not be considered in this context. This is because what is seen as related to the macroscopic shape of the associated diaphragm is the thickness of the damping layer (thus, the change in diaphragm geometry contributed by the weaving properties of the fibers). Flatten / ignore). However, the thickness of the damping material may be selected to be thicker at specific points, for example, in or within the region of intersections / nodes of vibration where breakups are observed. Therefore, there is a (middle) average thickness of the damping material, which is more than 10% greater than the (intermediate) average thickness of the damping material at different contact areas between the facing surface and the damping material, the backward facing. There may be a region that represents more than 10% of the area of contact between the surface and the damping material (and more than 10% of the total contact area). The thickness of the damping material may vary monotonically with increasing distance radially over at least 5% of the diameter of the diaphragm.

According to another aspect of the invention, there is also provided a method of manufacturing a speaker diaphragm for use, for example, as the speaker diaphragm described or claimed herein. Such a method may include applying a liquid damping material to a woven fiber that can be rotated. Rotating the woven fiber can help promote uniform application of the liquid damping material. The woven fiber body can be rotated at a relatively slow angular velocity, such as less than 100 rpm, when the liquid damping material is first deposited on the backward surface (eg, in a swirl pattern). Subsequently, when the woven fiber is rotated to promote uniform application of the liquid damping material onto the rearward surface, the woven fiber is at a relatively high angular velocity, eg, about 100 rpm to 1000 rpm). Can be rotated at speed. The woven fiber body may be rotated above 500 rpm during the step of rotating at a relatively high angular velocity. The process of rotating at a relatively high angular velocity is a first step of rotating at a first speed between about 100 rpm and 500 rpm, followed by a second step that is more than 50% faster than the first angular velocity and preferably faster than 500 rpm. It may include a second step of rotating at an angular velocity.

There may be a step to cure the damping material so that it changes from a liquid material to a solid (non-fluid) material. The liquid damping material can be applied in the form of an emulsion, eg, a water-based emulsion. The step of curing the damping material can be performed at a temperature below 100 degrees Celsius. If the damping material contains moisture, such as a water-based emulsion of PVA material, curing at a relatively low temperature may be important. The PVA layer can be cured between 40 and 80 degrees Celsius.
This method can be performed to make a speaker diaphragm having a woven fiber body made of a non-metal fiber material. The method of manufacturing a speaker diaphragm may include, for example, a step of attaching a metal coating to a non-metal fiber material of a woven fiber body. The step of adhering the metal coating can be performed using a thin film deposition method.

According to another aspect of the invention, there is also provided a speaker drive unit comprising a diaphragm according to any aspect of the invention described in the claims or described herein. Such a speaker drive unit may be configured for use as a midrange drive unit for a hi-fi speaker. The speaker drive unit may have an operating range over a frequency band including a frequency of 20 Hz. The speaker drive unit may have an operating range over a frequency band spanning a height of at least 6 kHz, and optionally at least 8 kHz. For example, the operating range may include 200 Hz to 5 kHz. If the diaphragm of the speaker drive unit has a diameter of less than 80 mm, the drive unit may have an operating range over a frequency band spanning a height of at least 10 kHz, and optionally at least 15 kHz.

According to yet another aspect of the invention, there is also provided a speaker enclosure comprising a speaker drive unit according to any aspect of the invention described in the claims or described herein.
Of course, it will be appreciated that the features described with respect to one aspect of the invention may be incorporated into other aspects of the invention. For example, the methods of the invention can include any of the features described with respect to the apparatus of the invention and vice versa.
Next, as a mere example, embodiments of the present invention will be described with reference to the accompanying schematic drawings.

It is a perspective view of the speaker housing which incorporated the woven fiber cone by 1st Embodiment of this invention. It is a figure which shows the direction of the fiber of the woven fiber cone of FIG. It is a side view of the cone of FIG. It is a figure including the enlarged view of a part of the woven fiber cone of FIG. It is sectional drawing of the part of the woven fiber cone shown in FIG. 4 along the plane represented by line AA of FIG. FIG. 5 is an enlarged cross-sectional view of one of the long objects of the material of FIG. It is a figure which shows the frequency response curve which compared the acoustic performance of the speaker of FIG. 1 with the equivalent speaker of the prior art. It is a figure which shows the frequency response curve which compared the acoustic performance of the speaker of FIG. 1 with the equivalent speaker of the prior art. It is a flow chart which shows the manufacturing method by 2nd Embodiment of this invention.

FIG. 1 shows a hi-fi speaker housing 2 in the form of a cubic cabinet 4 as a whole. The cabinet 4 houses the mid-range / low-range drive unit 6 and the tweeter 8. The speaker is ventilated by the forward facing port 10. The drive unit 6 includes a cone-shaped diaphragm 12 that has an overall concave shape when viewed from the front (as shown in FIG. 1). The diaphragm has a diameter of about 150 mm (6 inch drive unit) and operates over frequencies in the range of 20 Hz to 6 kHz. The diaphragm is formed from woven fiber cones as schematically shown in FIGS. 2 and 3, with FIGS. 2 and 3 showing the cones as front and side views, respectively. Thus, there are adjacent fiber strips 14 extending substantially parallel to each other, and these fiber strips 14 are other corresponding adjacent fiber strips extending laterally to them. Weave in and out to form a woven mat. The lengths 14 of the fibrous material are curved and intersect each other at different angles to define the desired (concave) conical shape of the diaphragm. The diaphragm 12 defines a forward-facing sound emitting surface and a backward-facing surface that supports the damping material. FIG. 2 shows the range in the length direction of only some of the long fibers 14 and shows the non-linear shape of the long fibers of the diaphragm 12.

The overall concave shape of the cone-shaped diaphragm 12 is formed by a wall extending 360 degrees around the central axis 12a, and the wall 16 has a convex shape that is gently curved when viewed in cross section. It will be seen from FIG. FIG. 3 also shows a forward facing sound emitting surface 22 (also seen in FIG. 1) and a rear facing surface 24 of the diaphragm.
FIG. 4 shows an enlarged view 18 of the cone 12 and a part thereof. As can be seen from FIG. 4, each fiber strip 14 has a space 20 between the substantially parallel adjacent fiber strips 14 extending in a given direction. It is woven with a relatively coarse weave. FIG. 5 shows a very schematic cross section of a long piece 14 of three parallel fibrous materials, which cross section is along line AA shown in FIG. The forward-facing sound emitting surface 22 is located at the top of FIG. 5, while the rear-facing surface 24 is located at the bottom of FIG. The layer of woven glass fiber material has a thickness Tf of about 0.2 mm to 0.3 mm. The rearward surface 24 of the diaphragm supports the layer 25 of the damping material, which fills the space 20 between the strips 14 of the woven fibers. The damping material is in the form of a cured PVA polymer and has a mass of ^{about 240 g / m 2.} The damping material has an average thickness Td of about 0.2 mm to 0.3 mm, which is not so different from the thickness Tf of the glass fiber layer. The cured PVA layer 25 fills the gaps 20 between the lengths 14 of the fibrous material and thus acts as a sealant (the cone would be full of holes without the sealant).

A long piece 14 of a single fibrous material is shown in cross section in FIG. The length of the fibrous material comprises a collection of individual glass fibers 26 (not shown individually in FIG. 6) arranged in parallel to form the threads 28. The woven glass fiber has an open weave with a mass density of ^{about 120 g / m 2 (when dried).}
The gap 20 between the long fibers 14 has a width of about 400-500 μm. The fibers 26 forming the threads 28 are embedded in the resin substrate 30, the outer surface of the resin substrate 30 is coated with the thin layer of aluminum 32, and the thin layer of aluminum 32 is protected by the layer 34 of the lacquer. The amount of resin used per unit area alone is less than the amount ideally required to provide the desired stiffness for the fiberglass layer. However, the layer 34 of the lacquer contributes to the rigidity of the woven fiber material and has a mass per unit area that is less than that of the resin but still comparable. The combined mass of resin and lacquer per unit area will typically be in the range of ^{20-60 g / m 2, depending on the individual application.} (Therefore, the woven glass fiber containing the resin and the lacquer has a mass density of ^{about 160 gm 2} ± 20 g / m ^2). The aluminum layer 32 is about 0.1 μm thick and therefore has a negligible mass compared to the mass of the other component materials of the diaphragm. The presence of layer 32 of aluminum provides opacity, without which the PVA layer 25 behind the glass fiber thread and / or the resin substrate 30 around the glass fiber thread would be desired. Can be exposed to more light and / or become more visible than. The aluminum layer 32 has a silvery appearance and provides the threads with a glossy, highly reflective outer surface. The thread weave reflects the incident light in a variety of different directions, giving the diaphragm a sparkling or shimmering appearance. Warps and wefts capture light in various ways, which also contributes to a visually noticeable appearance. In addition, slight changes in viewing angle can have a significant effect on how light is reflected, which is also a slight relative movement, especially when viewed with both eyes and / or between the observer and the diaphragm. It leads to the diaphragm having eccentric optical properties and appearance for the speaker diaphragm when viewed with.

The amount of PVA damping material used in the embodiments described herein provides improved performance of the diaphragm with respect to mechanical resonance (also referred to as breakdown). Proper handling of mechanical resonance is very important for the performance of the speaker diaphragm. For lower frequency units operating at frequencies up to about 500 Hz, the correct shape and material can be used to design the cone with mechanical resonance out of band. Material modulus (Young's modulus divided by density) is a good measure for quantifying the stiffness of a structure. By choosing a material with a high modulus of elasticity (such as aluminum or carbon fiber), the cone breakup is raised far above 500 Hz, so the unit operates only in a piston-like manner. For mid-range or low-to-mid range drive units, those units must cover a wide range of frequencies, for example 20Hz to 6kHz, which designs cones that do not show breakup in this (wide) band. Dealing with the problem is not so easy, as it makes it more difficult to do. The anisotropic nature and other mechanical properties of the Kevlar weave of prior art diaphragms have been used to alleviate problems with breakup modes in the operating frequency range.

FIG. 7 is measured by the microphone position along the axis of the vibrating plate of the first embodiment at a distance of 1 meter from the plane of the outer diameter of the vibrating plate while increasing the frequency (along the x-axis) of the sinusoidal input signal. The frequency response curve 50 is shown as a graph of the sound pressure level (along the y-axis). For comparison, the corresponding frequency response curve 52 for speakers using B & W Kevlar cones of comparable diameter is also shown in the graph, which is otherwise consistent in all respects. A portion 54 of the graph of FIG. 7 is shown in the enlarged view of FIG. It can be seen from FIGS. 7 and 8 that the frequency response curve 52 of the B & W Kevlar cone is relatively flat over the range of 200 Hz to 6 kHz, but there is room for further improvement. PVA-based damping materials have already been used in Kevlar diaphragms to achieve damping, but this embodiment uses much larger amounts than those made from Kevlar. Proposed in conjunction with glass fiber woven cones. Surprisingly, the use of fiberglass instead of Kevlar fiber can give better results when accompanied by the use of much larger amounts of PVA material. Therefore, it will be found that the frequency response of the diaphragm of the first embodiment (see curve 50 in FIG. 8) is superior to the frequency response of the Kevlar diaphragm (see curve 52 in FIG. 8). .. The frequency response of the Kevlar diaphragm has two peaks 56 around 3.5 kHz and 5 kHz, but the frequency response of the diaphragm of the first embodiment is flatter at such frequencies. The frequency response of the diaphragm of the first embodiment (see curve 50 in FIG. 8) may be as flat as the frequency response of the Kevlar diaphragm (see curve 52 in FIG. 8) at lower frequencies. , As can be seen from FIG.

The type of high attenuation polymer material used, such as PVA material, has a high dynamic loss rate (> 0.5 kHz in the first embodiment above) in the frequency band of interest (around 3.5 kHz and around 5 kHz in the first embodiment above). ) Can be presented. The dynamic loss rate can be measured by the DMTA (Dynamic Thermomechanical Analysis) test. Such tests are carried out at 25 degrees Celsius for convenience.

FIG. 9 is a flow chart showing the method according to the second embodiment of the present invention. Therefore, as a first step 162, a disc-shaped woven glass fiber mat is provided, in which a long piece 114 of a bundle of aligned glass fibers is woven to form a fiberglass mat. As a next step 164, the fiber material is coated with resin so that the fibers are coated (and partially pre-impregnated) with uncured resin 130 (thus forming a "prepreg" mat). Will be done. The resin-coated mat is then heat-treated in a vacuum-forming molded appartus using a mold that transforms the resulting resin-injected glass fiber mat into the required cone shape of the diaphragm. Will be done. Once the resin is cured, gaps 120 remain in the product between the elongated bundles of resin-injected glass fibers. Then, during the next step (enclosure 166 of FIG. 9), a metal deposition system is used to attach the aluminum coating 132 to the long fiber. The lacquer 134 is then attached to the metal coating using a lacquer spraying system (step 168). A thick layer of PVA material 125 is then attached to the back of the cone of material using the cone-spinning application system, which is described in more detail below (step 170). The cone is then trimmed and integrated into the loudspeaker drive unit in a conventional manner in the art.

The result of the cone-rotating PVA attachment step 170 is that of a large amount of liquid PVA (PVA retained in a water-based emulsion) to the back of the inverted cone using centrifugal force to spread the liquid over the entire surface of the cone. It is a deposit. This is achieved as follows. A continuous ball of liquid (PVA) is extruded and deposited in a vortex path on the back surface of a cone of material rotating at a low speed (less than 100 revolutions per minute). An air flow is used to disperse the liquid over the surface of the cone to create a continuous, seamless liquid coverage on the cone. The airflow used also pushes PVA into the gaps in the weave of the woven fiber material. The cone is then rotated at high speed in a two-step process as follows. The first stage of rotation is an attempt to level the PVA throughout the cone prior to the second stage. The first stage of rotation aims to remove any islands of non-PVA for the second stage to rotate properly. The speed of rotation in the first stage is about 150 rpm and lasts approximately 5 seconds. The second stage of rotation is 750 rpm over a period of about 5 seconds (although for larger diameter cones, a longer duration may be required). These steps of high speed rotation have a surprising effect on leveling the PVA over the entire surface of the cone, providing a clean finish with a relatively constant PVA thickness over the entire area of the cone. The PVA is then rapidly cured at about 65 degrees Celsius to dry the liquid so that it can be handled and to reduce the risk of PVA flowing and losing its shape. To reduce the risk of boiling water in the emulsion, a relatively low air temperature (<100 ° C.) is used to cure the PVA. In this embodiment, the PVA polymer used has a loss rate of> 0.5 at 5 kHz, 25 degrees Celsius. The PVA layer is deposited to form two-thirds (two-thirds) of the total mass of the cone. Having the cone forming a portion of the PVA layer that is significantly greater than half the mass of the cone provides a particularly beneficial level of damping, as described above. The PVA layer acts like a free-layer damping system, but also serves to seal the diaphragm (without the PVA layer, the cone would be full of holes).

Although the invention has been described and illustrated for a particular embodiment, it will be appreciated by those skilled in the art that the invention is suitable for many different variants not specifically shown herein. There will be. Next, as a mere example, some possible variants will be described.
It has been mentioned above that a particularly beneficial level of damping is provided by having a cone in which the PVA layer forms significantly more than half the mass of the cone. It will be appreciated that the PVA layer, which forms more than 62.5% of the mass of the cone, which would be determined to be well above half the mass of the cone, is particularly beneficial.

A constant thickness of PVA coating is not required. In practice, it may be advantageous to provide a PVA coating with varying thickness.
Materials other than PVA, such as other synthetic resin elastomer materials with high dynamic loss, can be used as long as they adequately result in high loss at the relevant frequencies. Materials with high viscosity and high hysteresis can be suitable alternatives. A vinyl resin-based thermoplastic material sold by Barrett Varnish Co as the Cone Edge Dampener E-5525 may be a suitable alternative. Another potential candidate is PVB (polyvinyl butyl), which is also usable as an emulsion and exhibits good damping properties.

Rather than using the PVA attachment method utilizing a rotating cone, the polymer may be attached by smearing, sponging, or otherwise adding a continuous layer of polymer. .. Many layers may be needed to obtain the required thickness.
As used herein, the term "woven material" (eg, in the context of "woven fiber material") is a mesh containing spaces between threads (or lengths of material) that form the main substructure of the material. Includes any material formed from threads or strips of material that are woven, knitted, or otherwise arranged to connect to form a fabric with a similar structure. In the embodiments described, the material used is in the form of a woven glass fiber fabric, but other woven or knitted materials may be used. For example, embodiments of the invention may have applications in which the fiber material is made from aramid (aromatic polyamide) fibers, or similar materials such as, for example, Kevlar.

The resin used for impregnation of the woven fiber material (this resin is used as a reinforcing material) may be a synthetic resin, for example, a phenol resin, an epoxy resin, or a melamine resin. However, any other flexible heat resistant thermosetting resin or high temperature thermoplastic resin may be used.
Where in the above description an integer or element having a known equivalent, an obvious equality, or a predictable equivalent is mentioned, is such an equivalent described as if it were individually described? As incorporated herein. The scope of claims should be referred to to determine the exact scope of the invention, and the exact scope of the invention should be construed to include any such equivalents. It is also noted that the completeness or features of the invention described as preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims. Will be understood. Moreover, such optional completeness or features may provide benefits in some embodiments of the invention, but may not be desirable in other embodiments and therefore may not be present. But should be understood.
Next, a preferred embodiment of the present invention will be shown.
1. 1. A speaker diaphragm having a forward-facing sound emitting surface and a backward-facing surface.
A woven fiber body that supports a vibration damping material that forms the shape of the diaphragm.
Equipped with
The mass of the damping material exceeds the mass of the woven fiber body by more than 25%.
Speaker diaphragm.
2. 2. The speaker diaphragm according to 1 above, wherein the woven fiber body is formed of a metal-coated non-metal fiber material.
3. 3. 2. The speaker diaphragm according to 2 above, wherein the thickness of the metal coating is less than 1 μm.
4. The woven fiber body contains a resin that contributes to the rigidity of the woven fiber body.
The metal coating is coated with lacquer, which also contributes to the rigidity of the woven fiber material.
The mass per unit area of the resin exceeds the mass per unit area of the lacquer by 5 times or less.
The speaker diaphragm according to 2 or 3 above.
5. The diaphragm contains a long piece of material that weaves in and out of each other to form the woven fiber body.
There are gaps between adjacent strips of material such that the woven fibers define an array of gaps, each gap having a maximum dimension of at least 100 μm.
The damping material fills substantially all of the gaps.
The speaker diaphragm according to any one of 1 to 4 above.
6. The speaker diaphragm according to any one of 1 to 5 above, wherein the damping material has a dynamic loss rate of at least 0.5 at a frequency between 1 kHz and 8 kHz.
7. The speaker diaphragm according to any one of 1 to 6 above, wherein the vibration damping material is a synthetic resin elastomer material.
8. The speaker diaphragm according to any one of 1 to 7 above, wherein the vibration damping material is a polyvinyl acetate material.
9. The speaker diaphragm according to any one of 1 to 8 above, wherein the thickness of the damping material changes monotonically as the distance increases in the radial direction over at least 5% of the diameter of the diaphragm.
10. The method for manufacturing a speaker diaphragm according to any one of 1 to 9 above, which comprises a step of applying a liquid system vibration material to a rotating woven fiber body.
11. The method for manufacturing a speaker vibrating plate according to any one of 1 to 9 above, wherein the woven fiber body forming the speaker vibrating plate is formed of a non-metal fiber material, and the method is vapor deposition. A method comprising the step of attaching a metal coating to the non-metal fiber material using a method.
12. A speaker drive unit comprising the diaphragm according to any one of 1 to 9 and / or the diaphragm manufactured by the method according to 10 or 11.
13. The speaker drive unit according to 12 above, which is suitable for use in a speaker housing as a mid-range drive unit.
14. A speaker housing including the speaker drive unit according to 12 or 13 above.
15. It is a speaker diaphragm,
Woven fiber with a forward sound emitting surface and a backward surface supporting the damping material
Equipped with
The woven fiber is formed of a metal-coated non-metal fiber material so that the diaphragm appears to have a shimmering appearance when illuminated by light.
Speaker diaphragm.

Claims (14)

A speaker diaphragm having a forward-facing sound emitting surface and a backward-facing surface.
A woven fiber body that supports a vibration damping material that forms the shape of the diaphragm is provided.
The woven fiber body is formed of a metal-coated non-metal fiber material, and the woven fiber body is formed of a metal-coated non-metal fiber material.
The diaphragm contains a long piece of material that weaves in and out of each other to form the woven fiber body.
There are gaps between the strips of adjacent material such that the woven fiber body defines an array of gaps, each gap having a maximum dimension of at least 50 μm.
Speaker diaphragm. The speaker diaphragm according to claim 1, wherein the thickness of the metal coating is less than 1 μm. The woven fiber body contains a resin that contributes to the rigidity of the woven fiber body.
The metal coating is coated with lacquer, which also contributes to the rigidity of the woven fiber material.
The mass per unit area of the resin exceeds the mass per unit area of the lacquer by 5 times or less.
The speaker diaphragm according to claim 1 or 2. The damping material fills substantially all of the gaps.
The speaker diaphragm according to any one of claims 1 to 3. The speaker diaphragm according to any one of claims 1 to 4, wherein the damping material has a dynamic loss rate of at least 0.5 at a frequency between 1 kHz and 8 kHz. The speaker diaphragm according to any one of claims 1 to 5, wherein the vibration damping material is a synthetic resin elastomer material. The speaker diaphragm according to any one of claims 1 to 6, wherein the vibration damping material is a polyvinyl acetate material. The speaker diaphragm according to any one of claims 1 to 7, wherein the thickness of the damping material changes monotonically as the distance increases radially over at least 5% of the diameter of the diaphragm. The method for manufacturing a speaker diaphragm according to any one of claims 1 to 8, wherein the method includes a step of applying a liquid system vibration material to a rotating woven fiber body. The method for manufacturing a speaker vibrating plate according to any one of claims 1 to 8, wherein the woven fiber body forming the speaker vibrating plate is formed of a non-metal fiber material, and the method is described. A method comprising the step of adhering a metal coating to the non-metal fiber material using a vapor deposition method. A speaker drive unit comprising the diaphragm according to any one of claims 1 to 8 and / or the diaphragm manufactured by the method according to claim 9 or 10. The speaker drive unit according to claim 11, which is suitable for use in a speaker housing as a mid-range drive unit. A speaker housing comprising the speaker drive unit according to claim 11 or 12. It is a speaker diaphragm,
It comprises a woven fiber body having a forward sound emitting surface and a backward surface supporting the damping material.
The long fibers woven to form the woven fiber are woven in and out of each other so that the forward sound emitting surface of the diaphragm has a non-smooth geometry at the local level.
The fiber strips are relatively such that there is a space between the fiber strips that are approximately parallel and adjacent to each other extending in a given direction, and that the woven fiber body defines an array of gaps. Woven in a coarse weave, each gap has a maximum dimension of at least 50 μm,
The woven fiber is formed of a metal-coated non-metal fiber material so that the diaphragm appears to have a shimmering appearance when illuminated by light.
Speaker diaphragm.

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